Production and stability of al and cu ultrafine particles in nanofluids

In this paper, a two step approach of synthesis of Al and Cu
ultrafine particles by mechanical alloying and then dispersing them in base fluid to prepare nanofluid has been reported. Ultrafine powders were prepared by milling elemental Al and Cu powders for 50 h in a planetary mill. After 50 h of milling, particles size has been reduced to 500nm for Al and 400 nm for Cu. It is also found from transmission electron microscopy (TEM) that each particles consists of large number of crystallites of size around 10-15 nm. Aiming at the dispersion of nano-Al and Cu is regarded as the guide of heat transfer enhancement, the stability of Al and Cu particles in water were studied under different pH values. It has been found from Nanozeta meter that Al suspension is stable at pH 2.5 and 9.5, whereas Cu suspension is stable at pH 2.3 and 9.8.